(1) Field of the Invention
My present invention is concerned with improvements in wall assemblies made of a plurality of composite wall panels, such as concrete wall panels, and components and connectors for such assemblies. My invention is also concerned with a method of making such composite wall panels by molding concrete to form a concrete panel.
My invention is particularly applicable for the provision of upstanding walls around oil tanks and the like hydrocarbon storage facilities, thereby to form part of a containment structure which can satisfy safety regulations for spills around such storage facilities.
(2) Prior Art
Various structures have been described in the prior art to form dikes and the like retaining means at storage facilities for hydrocarbon liquids and the like.
Thus, U.S. Pat. No. 3,940,940 of Mar. 2, 1976 to Joseph Edward Barrett is concerned with a method of protecting ground surfaces from spilled petroleum products, which method comprises covering the surface with a laminate including a polymeric membrane and a layer of fibre reinforced unsaturated polyester resin applied on top of the membrane. The membrane is impervious to the resin and sufficiently flexible to accommodate the ground contours. Barrett contemplates to provide a depression in the ground or to hollow out the storage area to make it saucer-shaped so that any spilled liquid in the area will gravitate to the centre of the hollowed region. Barrett then covers the depression with the laminate comprised of a cured glass fibre reinforced resin sheet on top of the membrane, to preclude penetration of hydrocarbon liquids into the soil. Accordingly, Barrett requires the digging of depressions in the ground, and such moving of earth is also practiced in building raised earth dikes around hydrocarbon storage facilities.
Thus, the U.S. Pat. No. 3,930,590 of Harold K. Ebbrell, issued Jan. 6, 1976, a storage facility for liquefied gas is disclosed in which a storage vessel is surrounded by a wall which forms a collecting space around the vessel. The surfaces of the ground of the collecting space and/or the wall comprise a layer of a heat insulating material, whereby any liquefied gas collected in the collecting space evaporates more slowly, thereby reducing the hazard from gas vaporized in the collecting space. reducing the hazard from gas vaporized in the collecting space.
U.S. Pat. No. 3,791,164 of Royce Jay Laverman, issued Feb. 12, 1974, is typical of the hitherto known practice of erecting fixed walls, and describes a storage tank facility for a liquefied gas having an enclosed tank, a vertical dike wall around and spaced from the tank side wall, thereby defining a well space between the dike wall and the tank side wall. The dike wall includes a plurality of vertically disposed conduits which communicate with the bottom of the well space, for venting cold liquefied gas vapors through such vertical conduits to the atmosphere.
U.S. Pat. No. 3,047,184 of J. C. van Bergen et al., issued July 31, 1962, discloses a wall surrounding a tank, which wall is built up of bricks, and the outside of the wall is surrounded by a wall of earth.
There has remained, however, the need to provide more economical yet effective protection around hydrocarbon-liquid storage facilities.
There is also nowadays the need to provide temporary or portable walls or panels for spill emergencies for in-situ type heavy oil recovery operations where permanent dike structures may be associated with correspondingly higher operational expense in first shaping and subsequently levelling earth structures or bricked types of retainment walls. More particularly, in closely-spaced well patterns, the creation and removal of dikes is a considerable economical concern with the operators.